In vivo experiment study of non-ablative photo-rejuvenation by using a 595-nm pulsed dye laser

The pulsed dye laser (PDL) has a history of producing safe and effective clearance of dermal vascular lesions; however, non-ablative treatments of rhytids with 595nm PDL are seldom studied. The purpose of our research is to evaluate the changes of skin elasticity, histology and the amount of hydroxyproline after 595nm PDL non-ablative rejuvenation and to offer references for effective clinical treatments. Forty KM mice were used for this experiment. Laser parameters were as follows: an energy fluence of 8 to 12J/cm², a pulse duration of 10ms, and a spot size of 7mm with 10% overlap. Skin elasticity was measured using Reviscometer® RVM 600. Specimens were sectioned for hematoxylin-eosin and Van-Gieson staining, and dermal thickness was recorded in an ocular micrometer. The amount of hydroxyproline in the dermis was quantified by the biochemical method. No marked side effects such as blister and purpura were noted during laser treatments. New collagen synthesized with an improvement in the organization of collagen fibrils. The 12 J/cm ² group improved skin elasticity by 31.7%, dermal thickness by 25.3% and the amount of hydroxyproline by 55.9%. There were the good correlations between dermal thickness and the amount of hydroxyproline. Therefore 595nm PDL non-ablative photo-rejuvenation is a safe and effective method for wrinkle reduction. And the energy level of 12 J/cm² has the greatest effect in improving skin mechanical properties and accelerating new collagen formation.